Methods

One hundred and ninety participants were recruited from primary care with knee osteoarthritis (OA) and chronic pain. PST consisted of a 100 Hz electric current delivered through four 30G acupuncture needles just touching the bone; the locations look (from the figure) like two extra points ‘Eyes of the knee’, ST36 and SP9. Stimulation was clearly perceptible but not painful and lasted 30 min. The groups were:

PST (once a week for 10 weeks) and PST boosters (once every 2 weeks twice, then once a month) for 6 months.

Control PST (four periosteal needles as above and brief electrical stimulation of two extra subcutaneous needles at control points in the upper pretibial region) once a week for 10 weeks.

PST for 10 weeks followed by sham control PST boosters for 6 months.

The primary outcome was the change in the Western Ontario and McMaster Universities Osteoarthritis Index pain score immediately after the 10-week intervention and 9 months after baseline. Responder rates according to the Outcome Measures in Rheumatology Clinical Trials-Osteoarthritis Research Society International criteria were also evaluated.

Results

Pain improved in all groups, with one significant difference between the groups—PST was superior to control at 9 months (figure 1). The responder rate showed non-significant trends in favour of group 1 (47.2%) compared with 30.9% in group 2 (control) and 40.7% in group 3.

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